JPS613885A - Manufacture of thin film by atomization - Google Patents

Abstract

PURPOSE:To form a thin film having a uniform thickness at a good yield on the surface of a substrate by allowing an atomized raw material soln. to rise gently from the lower part of a substrate which is obliquely installed with the surface faced downward and is kept heated along the surface thereof. CONSTITUTION:The substrate 15 is obliquely installed with the surface faced downward by a substrate holder 16 in a reaction chamber 19 having a discharge port 11 and is heated to about 400-500 deg.C by a heater 17 from the rear side. On the other hand, the raw material soln. such as a chloride soln. of Sn or In is atomized by ultrasonic oscillation in an atomizing chamber 13 provided below the chamber 19 and is blown from below to above via a hozzle 14 to the surface of the substrate 15 by the blast from an air feeder 12 induced by a fan 18. The atomized raw material soln. is formed into the laminar flow rising along the slope on the substrate 15 surface and is gently moved from the lower part. The raw material soln. is thereby heated and dehydrated near the substrate 15 surface and is brought into reaction with the oxygen in the air, by which the thin oxide film of Sn, In, etc. is uniformly formed on the substrate 15.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method of spraying an atomized raw material solution onto a heated substrate to form a thin film of an oxide such as Sn or In on the surface thereof.

[Prior art]

A conventional thin film manufacturing method of this type and its apparatus will be explained with reference to FIG. 2. A substrate 5 is horizontally fixed to a substrate holder 6 installed within a reaction chamber 9. As shown in FIG. This substrate 5 is heated to 400 to 500° C. by a heater 7 from the back side (the side on which the thin film is formed is referred to as the “front side” and refers to the back side thereof). On the other hand, below the first reaction chamber 9, an atomizer 3 and an air supply device 2 are provided, and the nozzle 4 thereof is installed toward the surface of the substrate 5.

The raw material solution is usually a chloride solution of Sn, In, etc., which is atomized by an ultrasonic vibrator in an atomizer 3, and is sprayed from a nozzle 4 to the surface of a substrate 5 by a fan 8 provided in an air supply device 2. sprayed on. Here, a part of the raw material solution is heated near the surface of the substrate 5 to be dehydrated and vaporized, and reacts with oxygen and water vapor in the air to adhere to the surface of the substrate 50. Therefore, a thin film of Sn, In oxide, etc. is formed on the surface of the substrate 5.

[Problem that the invention seeks to solve]

However, in this method, most of the raw material solution sprayed onto the substrate 5 separates from the surface of the substrate 5 due to the reaction after colliding with the substrate 5, and is exhausted from the exhaust port 1 of the reaction chamber 9 as a mist. Does not contribute to the membrane. For this reason, only a portion of the raw material solution sprayed onto the substrate 5 forms a thin film, and most of it does not form into a thin film and is wasted.Therefore, in this conventional method, The yield of thin IA based on the input raw materials is extremely poor.

The disadvantage was that productivity was low.

Further, in the case of this method, the formation of a thin film is noticeable in the portion of the substrate 5 that is directly hit by the mist, and the growth of the thin film decreases rapidly as the distance from this portion increases. Therefore, a particularly thick film is produced in a specific narrow part of the film, and the odor thickness is very thin in other parts.Therefore, it is difficult to produce a thin film with a uniform thickness over a wide area. It has the following drawbacks.

This invention was made to solve the above-mentioned problems in the conventional atomized thin film production method, and aims to improve productivity by improving the yield of the thin film, and also to improve productivity over a wide range of the surface of the substrate. It is an object of the present invention to provide a method for producing a thin film that can produce a thin film having a uniform thickness over a wide range of regions.

[Failure to solve the problem]

Below, the configuration of the present invention will be described with reference to FIG. 1.9 A substrate 15 is placed in a reaction chamber 19 with its surface facing downward.
The surface of the board "5" is not horizontal.

Install at an angle. This substrate 15 is constantly heated from the back side to 400 to 500°C by a heater 17 installed above it, and an exhaust port is provided on the top surface of one reaction chamber 19, so that the air inside the reaction chamber 19 can be etc. to be naturally exhausted.

In this state, the nozzle 14 is installed facing the surface of the substrate 15, and the air supply device 12. The atomized raw material solution supplied from the atomizer 13 is gently sprayed.

Since the substrate is installed at an angle and is heated from the back side, natural convection occurs that rises along the substrate surface from the left end to the right end in FIG.

[For production]

A part of the mist-like raw material solution sprayed onto the surface of the substrate 15 is thermally decomposed when it comes into contact with the substrate 15, and a thin film of oxide or the like is formed on the surface.

Further, a portion of the raw material solution that has not adhered to the surface of the substrate 15 moves gently along the surface of the substrate 15 by riding on the natural convection. While moving, there are those that contact the surface of the substrate 15 and form a thin film, and those that thermally decompose while moving close to the surface of the substrate I5 and form a thin film of oxide or the like on the surface of the substrate 15. be. The mist that moves near the surface of the substrate 15 on the natural convection flows through thermal convection and concentration difference diffusion, and supplies raw material components to the surface while moving in a complex manner that includes a movement that is different from the flow direction of natural convection. is performed continuously. As a result, a thin film having a uniform thickness is formed on the surface of the substrate 15 along the slope.

From these effects, the elevation angle θ of the surface of base @15 is.

A suitable angle is about 5 to 75 degrees, which is convenient for the atomized raw material solution to move slowly along the same surface, and most preferably 10 to 60 degrees. However, the flow of the mist depends not only on the above-mentioned elevation angle θ, but also on various factors that affect the state of convection formed in the reaction chamber 19, such as the amount and velocity of the raw material solution and the temperature of the substrate 15. Therefore, it is necessary to appropriately select the optimum elevation angle θ while taking these conditions into account.

〔Example〕

Next, examples of the present invention and comparative examples thereof will be described.

(Example) Two square glass substrates 15.15 with a thickness of 1.0 fin and a length and width of 10 (1++s) were connected in a row and attached to the substrate holder 16 with an elevation angle θ in the direction in which they were connected.Furthermore, these substrates! 5
．． 15 was heated from the back side with a heater 16 so that the surface temperature was maintained at 400°C. In addition.

The elevation angle θ of the substrate 15 is 15', 26°, and 71°,
It was conducted in three stages.

The nozzle 14 is made of quartz and has a discharge port of 48φ, and is located 30 mm from the lower side on the center line of the glass substrate Fi15.
The discharge port was placed vertically at a distance of 10 mm from the surface.

The raw material solution used was 25 g of tin tetrachloride (pentahydrate), 1 g of antimony trichloride, and 4 ml of hydrochloric acid dissolved in 150 cc of pure water.
was sprayed from the nozzle 14 onto the surface of the substrate 15 at a rate of 2 cc per minute for 6 minutes to form a thin film of tin oxide.

Then, the thin film is formed by the ratio of the weight of the thin film determined by the difference in the weight of the substrate 15 before and after the production of the thin film to the weight of the raw material component in 12 cc of the raw material solution sprayed onto the substrate 15 during the 6 minutes, that is, the weight converted to tin oxide. The yield was determined and shown in the attached table. Furthermore, when we observed the state of the thin film on the surface of one substrate 15, we found that in all cases, circular interference fringes were observed centered on the position where the raw material liquid was directly sprayed from the nozzle 14, and further along the above-mentioned slope. A wide area surrounded by interference fringes was seen on the upper side.

Note that the spacing between the interference fringes in the latter is wider than in the former.

It was confirmed that the film thickness was relatively uniform.

(Comparative example) A thin film of tin oxide was prepared on the surface of the glass substrate 15 under the same conditions and method as in the above example, except that the substrate 15 was installed so that the surface was horizontal (elevation angle θ = 0), and the raw material was sprayed. The yield of the thin film was calculated and shown in the attached table. Further, when the state of the thin film of the substrate 15 was similarly observed, multiple circular interference fringes were observed centered on the position where the raw material solution was directly sprayed.

From these results, it can be seen that in the above example, a higher yield was obtained than in the comparative example, and a thin film having a relatively uniform thickness was produced over a wide range.

〔Effect of the invention〕

As explained above, according to the present invention, thin films can be produced with high yield, and thin films with uniform thickness can be produced over a wide range, thereby achieving the intended purpose. can be achieved.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing each side of an apparatus for implementing the present invention, and FIG. 2 is an explanatory diagram showing an apparatus for implementing a conventional method.

Claims (1)

[Claims] In a method of producing a thin film by spraying an atomized raw material solution onto the surface of a heated substrate from below to above, the substrate is installed with its surface facing downward and inclined, and the surface of the substrate is tilted. A method for producing an atomized thin film, which comprises gently moving an atomized raw material solution from the bottom of a substrate to the surface thereof while forming a laminar flow that rises along the surface of the substrate.